Since Alblaka thought about the implementation of a "Nano-Sword", at least one long-range weapon (able to deal heavy damage against a tin can aka nanosuit-user) should be considered, should be high-tier stuff (advanced circuits, energy crystals etc) should be added.
I mean if weapons are what we want, we should install a gun-mod, but IC != guns? right?
Back to the weapons:
Long-range-weapon:
The iron is expensive issue could be solved by actually making a Railgun, because the slugs can be made of other things than iron, because ... blah Lorentz force blah (i won't get in the details now, look it up on wikipedia) ... the slug doesn't need to be ferromagnetic.
On the other hand, a Gauß-Weapon with iron (or refined iron) slugs would be interesting, precisely because the fact of the expensive ammunition, not to mention the energy costs.
Flamethrower:
I don't think thats a necessary addition, the griefing is not a problem (simple .txt: allow_flamethrowers=true/false), but in my opinion the mining laser is enough for CQB.
Taser:
mhm, I don't get why i would need that thing if i have a chainsaw (or a Nano-Tech Sword).
Stational Laser Thingy:
i think the tesla coils already do the job, but a stationary mining laser (dealing nice amounts of damage to mobs) would be good, excavating of my bunkers would be a lot easier, ok i could use nukes, but to clean the mess up afterwards ....
sry for my possibly it is very late and i'm no native speaker